Phase I Study of Anti-CD22 Chimeric Receptor T Cells in Patients With Relapsed/Refractory Hairy Cell Leukemia and Variant
Background Hairy cell leukemia (HCL) is an indolent CD22+ B-cell leukemia comprising 2% of all leukemias. Most cases of HCL respond well to purine analog chemotherapy and harbor BRAF V600E mutation that can be considered for targeted treatment at the time of relapse. However, there are patients with high-risk HCL such as patients with BRAF wild type IGHV4-34 unmutated HCL who respond poorly to chemotherapy and have poor survival. HCL variant (HCLv), also brightly CD22+, resembles HCL morphologically but is more aggressive and responds poorly to standard purine analog chemotherapy. Patients have fewer options of targeted treatment partly due to wild type BRAF. We showed that the overall survival in patients progressed after cladribine-rituximab is less than three years. Moxetumomab pasudotox-tdfk is an anti-CD22 recombinant immunotoxin which in 2018 was FDA-approved for adult patients with relapsed/refractory HCL. However, there are patients with HCL and HCLv who progress after treatments with standard purine analog chemotherapy and moxetumomab pasudotox-tdfk, and in the case of classic HCL, even after BRAF +/- MEK inhibition. There is still an unmet need for new treatment options for those with relapsed/refractory disease. Adoptive cellular therapy with T-cells genetically modified using viral-based vectors to express chimeric antigen receptors (CAR) targeting the CD22 molecule have demonstrated dramatic clinical responses in patients with CD22+ acute lymphoblastic leukemia (ALL). Moxetumomab pasudotox-tdfk proved that CD22 is a potent target for HCL due to its ubiquitous expression in HCL and HCLv, and cellular therapy represents a promising target for those patients that have progressed after other treatments options with chemotherapy, immunotherapy and targeted therapy. This will be the first trial of anti-CD22 CAR T-cell therapy in the treatment of relapsed/refractory HCL and HCLv. Objectives To assess the safety and feasibility of administering escalating doses of autologous anti-CD22-CAR (M971BBz) engineered T-cells in subjects with HCL/HCLv following a cyclophosphamide/fludarabine lymphodepletion regimen. Explore whether the administration of anti-CD22-CAR engineered T-cells can mediate antitumor effects in HCL/HCLv. Eligibility HCL/HCLv, after prior treatment with, ineligible for, refusal of, or inability to obtain 1) Rituximab given concurrently with or sequentially after purine analog, 2) moxetumomab pasudotox-tdft, and 3) BRAF-inhibition. Need for treatment, either 1) ANC <1/nL, 2) Hgb <10g/dL, 3) Plt <100/nL, 4) HCL count >5/nL, 5) HCLv count doubling time <3 months, 6) symptomatic splenomegaly, 7) enlarging HCL mass > 2cm in short axis, 8) increasing lytic or blastic bone lesions. > 18 years of age. CD22 expression must be detected on greater than 15% of the malignant cells by immunohistochemistry or greater than 80% by flow cytometry No uncontrolled infection, cardiopulmonary dysfunction, or secondary malignancy requiring treatment. No chemotherapy, immunotherapy, or radiation therapy less than or equal to 3 weeks prior to apheresis. Design PBMC will be obtained by leukapheresis, CD3+ cells enriched and cultured in the presence of anti-CD3/-CD28 beads followed by lentiviral vector supernatant containing the anti-CD22 (M971BBz) CAR. On Day -4 (cell infusion is Day 0), patients will begin induction chemotherapy comprising fludarabine 25 mg/m2 on Days 4, 3 and 2 and cyclophosphamide 900 mg/m2 on day 2. The CD22-CAR T-cells will be infused on Day 0, with up to a 72h delay allowed for infusion of fresh cells or a 7 day delay if cells are cryopreserved, if needed for resolution of clinical toxicities, to generate adequate cell numbers, or to facilitate scheduling. A Phase I cell dose escalation scheme will be performed primarily using 2 dose levels (1 x 105 transduced T-cells/kg; 3 x 105 transduced T-cells/kg). If 2 of 2-6 participants at dose level 1 have DLT, safety will be evaluated in a de-escalated dose of 3 x 104 transduced T-cells/kg (plus minus 20%). Once the maximum tolerated dose (or highest level evaluated) is reached, with 0-1 out of 6 having DLT, an additional 4 participants will be enrolled to provide further assessment of DLTs and for determining a preliminary assessment of the efficacy of the therapy in this participant population. Participants will be monitored for toxicity, response and T-cell persistence as well as other biologic correlates. Accrual ceiling will be set at 23 to allow for a few unevaluable participants and screen failures.
Start: June 2021
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